In printing systems, such as in inkjet printing systems, one consideration of system design involves the alignment of the printhead nozzles accurately with regard to the scan-axis carriage positioning guide, typically a precision-ground, cylindrical rod or rail. In particular, it is intended that the printhead nozzles be accurately and stably aligned, ultimately, relative to the body of the supporting carriage which rides on this rail, and therefore, accurately and stably also with respect (both translationally and rotationally) to all three of the usual, three, mutually orthogonal reference axes that are associated with the carriage-rail-supporting frame in a printer. Alignment relative to the X axis herein refers specifically to locked alignment relative to the body of the carriage, recognizing that the carriage must move back and forth in the X direction during printing. The carriage is also conventionally permitted a certain amount of rocking about the X axis to deal with printhead print height matters.
The three reference axesxe2x80x94the X axis which extends (as just indicated) in the printhead scanning direction, the Y axis which extends generally in the direction that print media is advanced through the printzone in the printer, and the upright Z axisxe2x80x94all typically are carefully respected with regard to proper nozzle alignment so as to achieve, from that perspective, the highest possible printing quality. In the many and various printing systems which have existed in the art to date, this issue of aligning has continued to present challengesxe2x80x94challenges that relate to economy of manufacture, to maintenance and preparation of close tolerances, to minimizing the number of datuming regions that may be distributed in the carriage/pen/ink-supply interface structure, and to other things.
In relation to known alignment of printhead nozzles with respect to the carriage body in a printer, tolerances exist in what often constitutes an additive-error stack of tolerance interfaces which results from the presence of plural, successive datuming interfaces that co-exist between the printhead nozzles and the bearings which support the carriage body on the supporting carriage rail. This xe2x80x9ctolerance stackxe2x80x9d (sometimes referred to as a tolerance loop) is a potential, and often real, contributor to misalignment problems.
The present invention relates to a carriage for use in a printing device, the carriage including a carriage body with a bearing structure configured to support such carriage body for movement along a reference track. The carriage also includes a printhead anchored to the carriage body, and aligned directly relative to the carriage bearing structure.